The present invention relates to semiconductor devices, more particularly light-emitting diodes (LEDs) and laser diodes (LDs).
According to the present invention there is provided a semiconductor device having a window layer, a current spreading layer below the window layer and a cladding layer below the current spreading layer, wherein the band gap energy of the spreading layer is higher than that of the window layer and lower than that of the cladding layer and the carrier concentration of the spreading layer is lower than that of the window layer and higher than that of the cladding layer.